When cutting with a high-pressure, liquid-oxygen jet as is known, for example, from U.S. Pat. No. 4,765,846 , the pressure of the oxygen, which is kept at the boiling point in the tank, is raised to 500 bar by means of a high-pressure oxygen pump. The outlet pressure from the cutting nozzle is regulated by means of a relief valve. The great momentum results in a high cutting speed of this cutting process. For the purpose of eliminating the heat resulting from friction and compression forces, it is necessary to cool down the oxygen with a cooling medium, for example, liquid nitrogen. In order to keep the lines between the high-pressure pump, the cooling device and the cutting torch as short as possible, the required cooling device is mounted together with these other units on a shared frame and moved along with the guiding cutter. For this reason, this part of the system must be light and have a low center of gravity.
There is a cooling device known from U.S. Pat. No. 2,205,499, in which the spiral gas line to be cooled is submerged in an insulated container filled with liquid air. The use of such a design to cool a high-pressure liquid-gas line entails a large diameter of the line spiral due to the thick walls of the high-pressure pipe. For the same reason, the container in which the spiral is submerged also has a large diameter and, consequently, a large structural volume.
Moreover, the cooling medium situated in the center of the container does not contribute to the cooling process and has to be carried as "dead weight". This problem could be solved, for example, by inserting a displacement element into the container; however, such a solution still does not eliminate the large volume.